diff --git a/doc/ext/plot2rst.py b/doc/ext/plot2rst.py
index 92978723..65c77521 100644
--- a/doc/ext/plot2rst.py
+++ b/doc/ext/plot2rst.py
@@ -27,9 +27,10 @@ plot2rst_rcparams : dict
 plot2rst_default_thumb : str
     Path (relative to doc root) of default thumbnail image.
 
-plot2rst_thumb_scale : float
-    Scale factor for thumbnail (e.g., 0.2 to scale plot to 1/5th the
-    original size).
+plot2rst_thumb_shape : float
+    Shape of thumbnail in pixels. The image is resized to fit within this shape
+    and the excess is filled with white pixels. This fixed size ensures that
+    that gallery images are displayed in a grid.
 
 plot2rst_plot_tag : str
     When this tag is found in the example file, the current plot is saved and
@@ -73,7 +74,10 @@ import numpy as np
 import matplotlib
 matplotlib.use('Agg')
 import matplotlib.pyplot as plt
-from matplotlib import image
+
+from skimage import io
+from skimage import transform
+from skimage.util.dtype import dtype_range
 
 
 LITERALINCLUDE = """
@@ -160,7 +164,7 @@ def setup(app):
                          ('../examples', 'auto_examples'), True)
     app.add_config_value('plot2rst_rcparams', {}, True)
     app.add_config_value('plot2rst_default_thumb', None, True)
-    app.add_config_value('plot2rst_thumb_scale', 0.25, True)
+    app.add_config_value('plot2rst_thumb_shape', (250, 300), True)
     app.add_config_value('plot2rst_plot_tag', 'PLOT2RST.current_figure', True)
     app.add_config_value('plot2rst_index_name', 'index', True)
 
@@ -335,7 +339,8 @@ def write_example(src_name, src_dir, rst_dir, cfg):
     thumb_path = thumb_dir.pjoin(src_name[:-3] + '.png')
     first_image_file = image_dir.pjoin(figure_list[0].lstrip('/'))
     if first_image_file.exists:
-        image.thumbnail(first_image_file, thumb_path, cfg.plot2rst_thumb_scale)
+        first_image = io.imread(first_image_file)
+        save_thumbnail(first_image, thumb_path, cfg.plot2rst_thumb_shape)
 
     if not thumb_path.exists:
         if cfg.plot2rst_default_thumb is None:
@@ -345,6 +350,28 @@ def write_example(src_name, src_dir, rst_dir, cfg):
             shutil.copy(cfg.plot2rst_default_thumb, thumb_path)
 
 
+def save_thumbnail(image, thumb_path, shape):
+    """Save image as a thumbnail with the specified shape.
+
+    The image is first resized to fit within the specified shape and then
+    centered in an array of the specified shape before saving.
+    """
+    rescale = min(float(w_1) / w_2 for w_1, w_2 in zip(shape, image.shape))
+    small_shape = (rescale * np.asarray(image.shape[:2])).astype(int)
+    small_image = transform.resize(image, small_shape)
+
+    if len(image.shape) == 3:
+        shape = shape + (image.shape[2],)
+    background_value = dtype_range[small_image.dtype.type][1]
+    thumb = background_value * np.ones(shape, dtype=small_image.dtype)
+
+    i = (shape[0] - small_shape[0]) // 2
+    j = (shape[1] - small_shape[1]) // 2
+    thumb[i:i+small_shape[0], j:j+small_shape[1]] = small_image
+
+    io.imsave(thumb_path, thumb)
+
+
 def _plots_are_current(src_path, image_path):
     first_image_file = Path(image_path.format(1))
     needs_replot = (not first_image_file.exists or